Two-party quantum private comparison based on eight-qubit entangled state

The purpose of quantum private comparison (QPC) is to solve "Tierce problem" using quantum mechanics laws, where the "Tierce problem" is to judge whether the secret data of two participants are equal under the condition of protecting data privacy. Here we consider for the first time the usefulness of eight-qubit entangled states for QPC by proposing a new protocol. The proposed protocol only adopts necessary quantum technologies such as preparing quantum states and quantum measurements without using any other quantum technologies (e.g. unitary operations and entanglement swapping), thus the protocol has advantages in quantum device consumption. The measurements adopted only include single-particle measurements, which is easier to implement than entangled-state measurements under the existing technical conditions. The proposed protocol takes advantage of the entanglement characteristics of the eight-qubit entangled state, and uses joint computation, decoy photon technology, the keys generated by a quantum key distribution protocol to ensure data privacy. We show that when all single-particle measurements in the proposed protocol are replaced by Bell measurements, the purpose of the protocol can also be achieved. We also show that the proposed protocol can be changed into a semi-quantum protocol with a few small changes.